Co‐segregation of AFLP and RAPD markers to apospory in Guineagrass (Panicum maximum Jacq.)

Abstract

SynopsisA genetic linkage map of guinea grass ( Panicum maximum Jacq.) was generated with nine of the AFLP markers found to be associated with apospory. These aposporyassociated markers were assigned to a linkage group having previous association with microsporogenesis of the aposporous guineagrass cultivar 'Natsukaze'. An aposporous linkage group was constructed utilizing 38 AFLP markers. Embryo sac analysis revealed that sexual and apomictic embryo sacs occurred at a frequency of 1 : 1, indicating simple inheritance of a single major gene controlling apospory in guineagrass. In addition, utilizing 56 AFLP primer combinations and 41 RAPD primers, 39 linkage groups and 360 simplex marker loci were assigned to the genetic map of the 'Natsukaze' cultivar. These markers covered 1703.5 cM of the autotetraploid guineagrass genome (2n = 4x = 32), with an average spacing of 4.7 cM. These tightly linked markers to apospory locus in guineagrass could be a powerful tool for marker-assisted selection of apospory and map-based cloning of the apospory gene.

The Present Status of C₄ Tropical Grasses Breeding and Molecular Approaches

“…Since apomixis also enables more rapid and efficient breeding, if a gene for apomixis were discovered, transgenic apomictic crops would hold considerable promise. Accordingly, many research groups, including our own, have worked to isolation of apomixis genes, both through molecular marker analysis (Ebina et al 2005) and through gene expression analysis in apomictic flowers (Yamada-Akiyama et al 2009). Guineagrass is one of the model plants for apomixis in tropical grasses.…”

“…as molecular breeding tools for genetic improvement of brachiariagrass must be useful. The breeding population in Thailand was analyzed using AFLP analysis for apomixis, as was done in guineagrass (Ebina et al 2005). First, seven obvious apomictic plants in the first 40 progeny (among 250 total progeny) were selected.…”

“…Some efforts have also been made to perform crossing in guineagrass (Bhandari et al 2011) and brachiariagrass (Felismino et al 2010, Miles et al 2004) species, but their polyploidy, high sterility, outcrossing, and apomixis hinder the development of new cultivars. Some breeding progress has been made using molecular biology methods in addition to conventional methods (Ebina et al 2005, Tsuruta et al 2011. These molecular tools are particularly powerful for obtaining information on their genetic information and inheritance, which has usually been insufficient to improve the key traits of tropical grasses.…”

“…In guineagrass, a forecast by designed breeding is hardly prevented by their apomixis trait, but the use of molecular tools means that breeding is no longer hindered by the presence of apomixis. The improved digestibility is one of key areas of focus in guineagrass, while in brachiariagrass, the marker-assisted selection (MAS) method used for guineagrass was applied (Ebina et al 2005), spawning faster breeding. In sorghum, the lignification mechanisms have been revealed by molecular techniques (Tsuruta et al 2010) and used to produce higher-quality forage cultivars.…”

Mapping and Haplotyping of the Flanking Region of the Polyembryony Locus in Citrus unshiu Marcow

“…In guineagrass, many markers linked to the apomixis locus were obtained by bulked segregation analysis (Ebina et al, 2005). In such studies of grass species, it has been widely observed that recombination in the region near the apomixis locus was strongly suppressed (Ozias-Akins et al, 2003).…”